How can a woman know that Allah loves her, is pleased with her, and has accepted her repentance, especially since she feels unable to persevere in seeking forgiveness due to life's fluctuations, and fears she will not be able to serve the religion because she remembers her past sins?

It is not permissible to combine two prayers without a valid excuse, and doing so is considered one of the major sins. Some scholars have permitted breastfeeding mothers to combine prayers due to the difficulty of cleaning clothes. If there is a valid excuse for combining prayers, then there is no harm; otherwise, each prayer must be performed at its appointed time: "Indeed, prayer has been decreed upon the believers at specified times." (Quran 4:103). However, if the combination is merely nominal, by performing the first prayer at the very end of its time and the second at the very beginning of its time, then there is no harm. As for past sins, they do not prevent one from becoming righteous and serving the religion, for repentance wipes away evil deeds: "Say, 'O My servants who have transgressed against themselves [by sinning], do not despair of the mercy of Allah. Indeed, Allah forgives all sins. Indeed, it is He who is the Forgiving, the Merciful.'" (Quran 39:53). Strive in obedience to Allah and do not despair, for good deeds erase bad deeds. If Allah uses you in His obedience, this is a sign of goodness. The servant's standing with Allah is commensurate with Allah's standing in the servant's heart, and whoever wishes to know his standing with Allah should look at what Allah has engaged him in.